Increased conductivities of Cr doped Al2−xCrxO3 powders due to band gap narrowing

A high Cr content in the synthesized Al2−xCrxO3 materials was achieved via a new synthesis route, the self propagating combustion method, for investigation of the effect of Cr substitution on the electrical, optical band gap and structural characteristics of the modified Al2O3 materials. X-ray diffraction (XRD) results showed that all the samples were pure and that Cr was successfully substituted in the crystal lattice. The cell parameters and volume are linearly dependent on the Cr content. AC impedance spectroscopy results show that conductivity of the Cr doped samples increases exponentially with Cr content. This is attributed to band gap narrowing of the Al2−xCrxO3 powders as obtained from UV-visible spectrophotometric studies.